An Accurate On-Machine Surfaces Measurement Using FEA Method

Kinematic touch trigger probes are widely used in medium to large-scale industries for part setup and quality assurance due to their economical advantage over noncontact probes. These tools significantly reduce the lead times during part setup and inspection processes. However, the sensing distance error caused by the electro-mechanical switching mechanism substantially influences the measurement results and thus needs to be calibrated before utilizing the probe. In this thesis, an accurate on machine surface measurement process based on finite element method is implemented to predict the sensing distance of a kinematic touch trigger probe based on Renishaw’s OMP40-2 probe, FEA simulation model is verified using the existing mathematical model and experimental data. A novel mathematical model is developed taking into consideration the sliding effects of the probe tip on the part surface. Three cases of surface measurement are considered, which are, vertical surface, inclined surface, and a curved surface, followed by FEA methods in finding the sensing distance and the spindle travel to compensate for the surface measurement error. A newly developed surface measurement model is verified using the experimental results. Two case studies are presented, inclined surface measurement results with sliding effects are compared with that of an existing model and two curved surfaces (Ellipsoidal and Convex) cases are studied. Finally, inclined surface and ellipsoidal surface results are compared to study the effects of surface curvature on the sensing distance